Benzyl bromide by light-driven semi-batch bromination of toluene, HBr absorption and batch distillation (1000 t/a)

Overview

What goes in and out

Utilities: Electricity (0.160 kWh/kg: the lamps of R-101 (0.118 kWh/kg), the agitators and the vacuum pump (ASSUMED)), Steam (0.431 kWh/kg of LP steam 450 kPa(a): R-101's heat-up and the still with its column (the reboilers from core's models, DESIGN.md D-009)), Cooling water (0.666 kWh/kg removed: R-101's jacket and lamp wells, the reflux condenser, the absorber, the still's and the column's condensers and coolers), Chilled water (0.046 kWh/kg removed by brine at 258 K: the vent condenser and the column's condenser and cooler during the forerun (the registry has chilled water, not brine: closest entry))

Show in the process graph

Reactions

Each reaction's page has the conversion, heat of reaction, catalyst and sources this process states, next to those of other processes with the same reaction. All reactions

Life cycle assessment

Maturity and review

Design maturity Concept (claimed): An idea or first flowsheet; numbers are rough. Concept batch PFD with closed mass, component and element balances (cheme validate, cheme process streams: 3 blocks and 10 steps within tolerance). The semi-batch R101 with its HBr vent carrying the content's vapour through its vent condenser E-102 (from its ASSUMED effective rate laws, Raoult over an ideal liquid; core ADR 0062), the strip ST101 (one Rayleigh stage), the forerun ST102 and the main cut ST103 through the still's column (5 theoretical stages, reflux 2 and 0.5, ASSUMED; Diwekar's shortcut, ADR 0061; all on Raoult's law with NIST Antoine constants, the ideal liquid and benzal bromide's vapour pressure ASSUMED), the mixers, the splitter and the toluene recycle (converged at its tear stream S2, ADR 0060) are calculated by cheme process propagate, which also writes the model duties: E-102's (Q4), the stills' reboilers (Q7, Q9, Q14) and the column's condensers (Q10, Q11; ADRs 0059, 0061, 0062). scripts/balance.py gives the feeds for 1000 t/a, the brine vent condenser E-103 (a flash as core's vent condenser), the absorber water, the mixing and bubble-point temperatures and the other duties (no property package of core covers these liquids); the stills' charges' sensible heat, 2.84 kW less steam, is left out and recorded (DESIGN.md D-009). The recipe's year-average rate of the product agrees with the flowsheet (no cheme.recipe-basis finding); the recipe sizes R-101 (4 m3), its jacket check passes, and the stills' times come from their boil-up. Thermal screening (cheme process reactor-hazards): dT_ad 44.2 K, accumulation 1.66 %, MTSR 363.9 K against an MTT of 383.8 K (hazard.mtt: the boiling point of toluene); no criticality class without a TD24 (1 or 2 if the TD24 lies above the MTSR, 5 if below). With k/10 the MTSR is 370.3 K, with k/100 396.1 K, above the MTT, where the content boils (DESIGN.md D-011). At the MTSR the gas leaves with the content's vapour at 59.6 m3/h, and at most 72.8 m3/h for a cooling failure earlier in the dosing, within R-101's off-gas capacity of 90 m3/h (ASSUMED: 1.2 times the largest, rounded up to the next 5 m3/h); at k/10 102.3 m3/h exceeds it, and the blocked-vent case (about 0.24 MPa in the head space in the design case, 2.3 MPa at k/10) needs a relief device (open findings, DESIGN.md D-014). Preliminary gate-to-gate LCI with the per-batch nitrogen; the bromine linked to bromine-1, the toluene to btx-1, the nitrogen to asu-1, the other backgrounds gaps; the hydrobromic acid a co-product by mass of its HBr (shares 0.6572/0.3428). cheme maturity reaches no level (assumed feeds, kinetics and separations); the claim `maturity: concept` is the lowest value of the schema, not an evidenced level. Not reviewed. Needs cheme-as-code 1.10.0.

Open items

Sources

Engineering project

Benzyl bromide · cheme-as-code>=1.10

Library version

a3c52e4 (process last changed in a3c52e4)

Drawings rendered by

cheme 1.6.0 (pyDEXPI 2.1.0)

Data

Catalog record (JSON) · CC-BY-4.0

Files

View the files on GitHub · change history and authors

References

• Plander, E.; Zahalka, J.; Formacek, V. (1970) US 3 528 899 A, Method of brominating the side chain of an alkyl benzene (background: light-, heat- and peroxide-activated processes; Example I: bromine dosed into toluene at the rate it reacts, HBr withdrawn, product cut at 190-210 C, about 90 % on toluene)
• PubChem CID 7498, Benzyl bromide (identity; HSDB: methods of manufacturing, physical properties, reactivity and hazards)
• NIST Chemistry WebBook, SRD 69: toluene, bromine, benzyl bromide, benzal bromide (Antoine constants, heats of vaporization, boiling points, formation enthalpies)
• Stoessel, F. (2008) Thermal Safety of Chemical Processes, Wiley-VCH (accumulation and MTSR of a semi-batch; method reference, not data) · doi:10.1002/9783527621606

How to cite

@unpublished{schweidtmann_process_atlas,
  author = {Schweidtmann, Artur M. and Weber, Jana M.},
  title = {{Process Atlas: an open, git-native, reproducible library and life cycle inventory of chemical processes (working title)}},
  year = {2026},
  url = {https://atlas.cheme-as-code.org},
  note = {in preparation}
}

@misc{schweidtmann_cheme_as_code,
  author = {Schweidtmann, Artur M.},
  title = {{ChemE-as-Code: An Open-Source Platform for Agentic AI in Chemical Engineering}},
  year = {2026},
  eprint = {2611.07947},
  archivePrefix = {arXiv},
  doi = {10.48550/arXiv.2611.07947},
  url = {https://arxiv.org/abs/2611.07947}
}